The field of the present invention is fuel mixing systems wherein proportionate amounts of lubricating oil and fuel are mixed and supplied to an internal combustion engine, typically a two-cycle engine.
Two-cycle engines generally require that lubricating oil be fed to them during running. Such has been accomplished in the past by placing a predetermined amount of oil into the fuel tank to obtain the required ratio, or through a separate oil reservoir which supplies oil to the combustion chamber through an intake manifold or mixing at the carburetor.
In the first system, it proves troublesome to mix fuel and oil in advance and further devices are required to make appropriate measurements and perform the mixing. Yet it still remains difficult to ensure a correct ratio.
In the second system, the amount of lubricating oil supplied depends upon the rotation of the engine and opening angle of the throttle; thus the actual fuel flow rate is not accounted for and a constant mixture ratio cannot be maintained. In absence of a constant ratio, either too much exhaust smoke may be produced due to overburning of oil or not enough oil may enter to properly lubricate the engine, resulting in premature wear.
Finally, any separate fuel and oil mixing system generally must surmount the problem of inaccurate mixing due to the small amounts of oil mixed at any one time. Thus, amounts mixed each time must be large enough to ensure a stable mixing ratio.